An exhaust manifold is coupled to a multi-cylinder engine body. The intake side of the exhaust manifold is connected to an exhaust port of a cylinder head, and the exhaust side of the exhaust manifold is connected to an exhaust path having a catalytic device. In an engine equipped with a turbo supercharger, the exhaust energy of the engine is used. In this case, the exhaust side of the exhaust manifold is connected to a turbine chamber of the turbo supercharger.
The exhaust manifold becomes hot at the time of driving the engine, which may thermally affect peripheral components. For example, a cylinder head cover mounted on the upper side of the cylinder head may be made of a resin material for weight reduction, and is thus likely to be thermally affected. Therefore, for heat insulation, the periphery of the exhaust manifold is covered by a heat insulator (manifold insulator). Patent Literature 1 discloses a heat insulation configuration in which an extension section is disposed at the upper ends of gaskets interposed between the connection sections of a cylinder head and an exhaust manifold, the extension section covering the upper side of the exhaust manifold.
Even when the manifold insulator covers the exhaust manifold, hot air cannot be completely confined in the insulator. The hot air in the manifold insulator may leak out from an unexpected gap to cause thermal damage to the peripheral components. Also in the heat insulation configuration disclosed in Patent Literature 1, it is not disclosed about how the hot air in the insulator should be released.